DB9 Form Factor USB-RS232 Replacement

If you’re attached to that favorite DB-9 interfaced device you should look into this part. FTDI is selling a USB-RS232 adapter as a replacement for DB-9 connectors. They come with USB male or female connections depending on the application and have the same serial footprint and pinout to which you’re accustomed. Using converter cables is just fine but this simplicity requires a few minutes of desoldering, rather than redesigning, etching, and populating a board in order to give that older design built-in USB connectivity.

[Thanks Juan]

31 thoughts on “DB9 Form Factor USB-RS232 Replacement

  1. Compare this to a 3~4 dollar cell phone usb/serial cable, and a standard panel mount mini usb at ~1 dollar, no thank you. I do not have a burning hole in my wallet.

    That said, it is ingenious.

  2. UNfortunately, those cell phone cables usually sport a PL2303 or other Chinese brand of USB-to-serial convertor chip. These seem to have trouble with at least my Linux-system at high baud rates. I usually use FT232-based boards: they aren’t cheap but I’ve been known to push 1MBit over them without dropping bytes.

  3. I bought a Nokia cable for $3, shipped.
    It was a piece of junk, even when it worked.
    It had Tx and Rx and GND, and that was it. The rest of the pins on the chip were under black epoxy, and the damn thing was too unreliable to use for anything important.
    Bought a $25 one with a warrantee and everything’s been perfect.

    Why would you want to have one expensive device attached to each older thing you want to use? A good cable is worth so much more.

  4. @Regulus –
    I agree, there is really no substitute a good Ser-USB adapter cable, especially if you are making connections to multiple devices as I do with satellite equipment.

  5. Some of you guys are missing the point. Sure, for the average hacker, these would not be cost beneficial, but for a manufacturer that has an in-production design using a DB-9 connector, this is a drop-in replacement to update the features of their product…

  6. Yeah, FTDI is awesome. Our products use a 2.5mm stereo mini jack for RS-232 output, and we have had to ship USB-serial adapters along with our 2.5mm-DB9 cable for the last few years. Then they came out with the USB-RS232 cable with the converter built into the USB plug, and we can now ship a much nicer looking cable to customers without having to modify our actual product at all!

    Many of you will say that $22 is a lot of money for something like this (the cables i mentioned are $22 also), but if this is a product for a real company that is just trying to cheaply move forward, this is worth every penny.

  7. Holy crap that’s cool. I almost want to drop one of those in an ancient ‘headless’ server I have sitting in a closet so I can actually get it up and running. :D

    But an FTDI cable would probably be more reasonable… Not as cool, but more reasonable.

    1. mafoose, i am wondering if you were ever able to update your megasquirt. i just recently stumbled upon this and thought it would be great as well, i have my ms2 v3 running my 1986 200sx turbo. thank you for any info

  8. It would have been even more awesome if we previously had RS232 to TTL modules in this form factor. Now we get to keep our rs232 interface circuits and certainly there are their counter pairs inside these modules, which makes two unnecessary level translations and pushes the price up. I like idea of small number of user accessible contacts, though. SSOP package kept me on the distance so far (I can’t be bothered to go through board design and manufacturing ordeal for my one-off projects). I’d rather have some fairly simple (from users’ POV) D+,D- -> Rx,Tx; 5V supplied; 8 pin IC; generic blackbox. That would at last be a MAX232 killer. Until something like that comes around, it will still be much simpler to ignore USB for all small projects and have one USB-to-serial cable handy.

  9. The Nokia cables are about £1 each off ebay (delivered) and work perfectly.

    The best thing to do is pop open the plastic housing on the USB end and access the PCB. It will have at a minimum RX, TX and GND. All but one of mine has a 5V pad but if your does not you can just take it off the USB plug if you need it.

    You can also replace the USB plug with a socket or wires quite easily, ideal for building into a project case.

    The FTDI chips they use are OK with both 5V and 3.3V signalling.

  10. I was down at FTDI today. These will not be shipping till June maybe July. The difference between the make and the female are the pins on the board side as they are flipped. They say they have gotten a lot of interest sine they announced them on their site.

  11. I’m eying these as an option for my MegaSquirt as well.

    That being said, I already have a FTDI USB-RS232 adapter cable, due to having gotten a few different flaky cheap adapter cables off of ebay and elsewhere.

    For some applications, the cheap implementations may work. For others that push higher data rates, and expect a solid connection, they can fail miserably.

  12. Hi FTDI here, We will have Stock in mid June, Yes they are $22 for one off, the reason being some of the components inside are expensive, and on Long lead times… due to the response we are trying to further increase production, if you are intending to use volume, please contact us.
    Best regards


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